Link adaptation, or adaptive modulation and coding, is a term used in wireless communications to denote the matching of the modulation, coding and other signal and protocol parameters to the conditions on the radio link. The performance of a wireless data communication system can be limited by path-loss, interference due to signals coming from other transmitters, sensitivity of the receiver, available transmitter power margin, and the like. A wireless local area network (WLAN) communication system can use an algorithm that adapts the modulation and coding scheme according to the quality of the radio channel, thereby improving the bit rate and robustness of data transmission. The performance of a communication system can be measured based on link data rate, network capacity, range, power consumption, and the like. The process of link adaptation is a dynamic one and the signal and protocol parameters change as the radio link conditions change. This is especially true for a mobile device, as a user's distance from a wireless access hub transmitter is likely to vary over time. Link adaptation can utilize channel state information provided by a transmitter, such as a WLAN access point, however legacy systems may not provide this state information. Accordingly, link adaptation can be provided based only on reception parameters and analytics determined by a WLAN node.
Mobile communication devices are typically powered by an included battery having limited capacity. One approach to reducing power consumption that has been proposed is to employ envelope tracking, wherein a voltage provided to an RF power amplifier is configured to track the actual waveform of the modulated radio frequency signal provided to an antenna. However, the envelope tracking approach is both difficult and expensive to implement, rendering implementation impractical. Accordingly, other techniques for reducing power dissipation in a wireless transceiver are needed. In some situations, it may be necessary to compromise data rate, range, and other performance metrics in order to conserve power. For example, a device may simply limit transmit power to a fixed, reduced, level.
The use of the same reference symbols in different drawings indicates similar or identical items.